Factors Influencing the Secretion of Nitrogen in Sheep Saliva

SUMMARY Urea was added to the rumen of three merino sheep at the rates of 5, 10 and 20 gm. daily to increase the overall nitrogen intakes from 10.7 gm. in the basal ration to 13·0, 15·4 and 20·0 gm. per day. A marked increase in the total amount of nitrogen secreted in parotid saliva was found to occur as the nitrogen intake of the sheep rose. A similar high correlation was found between the level of nitrogen intake and the amount of urea nitrogen secreted in the saliva daily. Between the highest and the lowest levels of nitrogen intake the magnitude of the increases were 0·26 gm. of total nitrogen and 0·18 gm. of urea nitrogen per gland per day. The concentration of urea nitrogen in the blood increased with the level of nitrogen intake of the sheep, but fluctuations in the level of blood urea could not be accounted for by nitrogen intake alone. A significant correlation was found between the concentrations of urea nitrogen in the blood and in the saliva. This offered a partial explanation of the higher concentrations of salivary urea resulting from the increased nitrogen intakes.